Believing in Jesus Christ as our Lord and Savior and repenting of our sins is a commandment from our Creator-God. Only through him we have forgiveness of our sins and peace with God.
Why Jesus?
Jesus alone is "the way and the truth and the life. No one comes to the Father except through me" (John 14:6). We know this because we have the testimony of the disciples who walked with the historical Jesus of Nazareth, witnessed his crucifixion (Luke 23:33), death (Luke 23:46), burial (Luke 23:53), resurrection (Luke 24:36), and ascension into heaven (Luke 24:51, Acts 1:9). In addition, countless believers in the last 2,000 years testify to the life-changing experience of being "born again to a living hope through the resurrection of Jesus Christ from the dead" (1 Peter 1:3, John 3:3). Jesus began his earthly ministry by proclaiming the gospel of God saying, "The time is fulfilled, and the kingdom of God is at hand; repent and believe in the gospel" (Mark 1:15).
Why Me?
We all have the same problem, namely, an inability to live as God originally intended (Psalm 53:2-3, John 4:24, Romans 3:11). The natural-born human cannot seek after the living God because of being born a slave to sin (John 8:34, Romans 7:14). The first man and woman, fashioned by God himself (Genesis 1:26-27), had only one restriction in their earthly paradise (Genesis 2:16-17). A single act of disobedience resulted in their spiritual death and separated them from the one who gave them life (Acts 3:15, 1 Corinthians 15:21-22). Similar to a genetic disorder that is passed down from parent to child, we inherited our ancestors' rebellious nature through their transgression (Romans 5:12). As far as God is concerned, we are either under Adam's or Christ's headship. Unbelievers remain under Adam's headship and are forever damned. Those under Christ's headship are forgiven of their sins and inherit eternal life.
Why Today?
No one knows when we will die (Ecclesiastes 8:8, Hebrews 9:27). Since we were made in God's image (Genesis 1:27), we are accountable to him. The Lord God is angry with humanity because of our sin (Deuteronomy 4:21, 25:16, 1 Kings 11:9, Proverbs 3:32, 11:20, 16:5, Psalm 7:11-12). John the Baptist, Jesus' relative (Luke 1:36), states that "Whoever believes in the Son has eternal life; whoever does not obey the Son shall not see life, but the wrath of God remains on him" (John 3:36, Psalm 2:12). The only way to be justified in God's eyes is by faith alone, trusting in the atoning work of his risen Son, Jesus Christ (Psalm 49:7, Romans 3:24-26). Jesus will one day return to the earth and judge both the living and the dead according to his Father's holy standard (John 5:22, Revelation 20:12-15). The penalty for rejecting God's free gift of salvation (Ephesians 2:8) is eternal punishment, while whoever receives Christ Jesus as Lord (Colossians 2:6) inherits eternal life (Matthew 25:46).
How Then?
Since Jesus already lived a perfect life and sacrificed himself on the cross (Luke 23:33, Psalm 22:1, Mark 15:34) to satisfy God's holy judgement for sin (John 1:29, Hebrews 9:26), the rest is relatively simple (Matthew 11:28-30, Romans 10:8, Deuteronomy 30:14). Respond to the Father and Son's call (John 3:16, 15:13) today by confessing with your mouth that, Jesus is Lord, and believe in your heart that God raised him from the dead, and you will be saved (Romans 10:9-10). The evidence of genuine faith is reflected in your commitment to repent of your sins (Romans 2:4) and love and follow Jesus from now on (Mark 8:34-37, John 8:31, James 2:22).
What's Next?
Congratulations! If you truly have believed Christ's gospel (1 Corinthians 15:1-4) and confessed his name (Matthew 10:32, 1 John 4:15, Revelation 3:5), then know that you have eternal life (1 John 5:13, 2 Corinthians 5:17-21), and will live forever in God's heavenly paradise when you die (Luke 23:42-43, Hebrews 11:16). You are now washed, sanctified, and justified in the name of the Lord Jesus Christ by the Spirit of God (1 Corinthians 6:11). Your assurance of eternal security comes from the inward motivation by the Holy Spirit to cry out, "Abba, Father!" (Mark 14:36, Romans 8:15, Galatians 4:6) and the accompanying cultivation of a life-long habit of good works (James 2:17). Jesus now desires that you be baptized in water as an outward sign of your internal baptism by the Holy Spirit (Matthew 28:19, 1 Corinthians 6:11). Study the Bible and find a local church that adheres to the gospel (1 Corinthians 15:1-8, Galatians 1:9), where you can "grow in the grace and knowledge of our Lord and Savior Jesus Christ. To him be glory both now and forever! Amen" (2 Peter 3:18).